Regenerative air preheater

ABSTRACT

In a regenerative air preheater of the stationary cylindrical regenerator chamber type, a rotatable heat-exchange element carrier is provided at the cold end of the regenerator chamber. The chamber wall has an aperture opposite the carrier through which access can be had to the heat-exchange elements in the carrier for their radial installation or removal.

United States Patent [191 Schluter et a1.

[ Mar. 26, 1974 REGENERATIVE AIR PREHEATER' Inventors: Siegfried Hans-Dietmer Schluter,

Wenden-Biggetai; Gerhard Kritzler, Freudenberg, both of Germany Assignee: Apparateban Rothemuhle Brandtt &

Krilzler, Rothenuhle, Postfach, Germany Filed: Apr. 6, 1972 Appl. No.: 241,604

Foreign Application Priority Data Apr. 6, 1971 Germany 2116728 US. Cl 165/4, 165/5, 165/10 Int. Cl. F28d 17/02 Field of Search 165/5, 8, 9, 10, 4

References Cited FOREIGN PATENTS OR APPLICATIONS Great Britain 165/10 684,797 12/1952 Great Britain 165/10 914,273 1/1963 Great Britain 165/5 1,045,974 10/1966 Great Britain 165/5 Primary Examiner-Albert W. Davis, Jr.

57 ABSTRACT In a regenerative air preheater of the stationary cylindricai regenerator chamber type, a rotatable heatexchange element carrier is provided at the cold end of the regenerator chamber. The chamber wall has an aperture opposite the carrier through which access can be had to the heat-exchange elements in the carrier for their radial installation or removal.

15 Claims, 9 Drawing Figures PATENTEU "AR 2 6 I974 H65 HIM.

SHEET 3 OF 4 Hum llllllllluj l REGENERATIVE AIR PREHEATER FIELD OF THE INVENTION The invention relates to a regenerative air preheater having a cylindrical regenerator chamber, one of the heat exchanging gases being led to and away from the axial ends of the chamber by coaxial rotating hoods.

BACKGROUND OF THE INVENTION In regenerative air preheaters having a stationary regenerator chamber, because the heat-delivering and heat-receiving gases pass in opposite directions through the regenerator chamber, one axial end of the chamber is the cold end. In the cold end the heated surfaces and the structure of the chamber are exposed to fouling and corrosion to a greater degree, since temporarily the preheater may be operated so that the heating gas is below its dewpoint in this end. Cleaning or replacement of the heated surface elements and of corrosionendangered structural parts is therefore required more frequently than for other parts of the chamber.

The heated elements, which may be metal or ceramic are contained in prefabricated units of convenient size. Hitherto the units have been installed in or removed from the stationary regenerative chamber from the gas inlet or outlet ducts. This requires stoppage of the preheaters operation.

It is an object of this invention to provide a regenerative air preheater in which the heater element units and corrosion-endangered parts of the structure at the cold end of the regenerator chamber are accessible and detachable so that their installation and removal can be effected from the outside, if required, during operation of the regenerative air preheater.

SUMMARY OF THE INVENTION According to this invention, there is provided a regenerative air preheater having a cylindrical regenerator chamber having two axial ends one being a hot end and the other a cold end, a coaxial rotatable hood at each said axial end to lead one of the heating gas and the heat-receiving gas to and away from the ends, a wall surrounding the said chamber, and an aperture of restricted arc length in the said wall adjacent the cold end, the said chamber being subdivided axially into two parts, both containing heater elements having heat exchanging surfaces, the said part at the cold end containing a rotatable heater element carrier, whereby access can be had selectively to the said heater elements in the said rotatable carrier through the said aperture for their radial installation or removal.

Preferably the rotatable part of the chamber is about 20 to 35 percent of the total axial length of the chamber between the hot and cold ends.

Preferably the rotatable carrier is partitioned by radial walls providing wedge shaped spaces, so that for installation and removal of assembled units of cold end heat-exchange units one such wedge shaped space is always presented to the access aperture. Preferably means are provided for closing the axial ends of the said wedge-shaped space which is accessible at a given time.

Preferably a disconnectable reduction drive from the hood drive is provided for driving the said carrier in rotation.

DESCRIPTION OF PREFERRED EMBODIMENTS By way of example, two embodiments of the invention will be described with reference to the accompanying drawings, in which:

FIG. 1 is a sectional elevation through the axis of a regenerative air preheater.

FIG. 2 is a sectional view showing on the left a section through the regenerative chamber of the heater of FIG. 1 along the line ll of FIG. 1 and on the right a section through the rotatable part of the chamber along the line II-ll of FIG. 1.

FIG. 3 is, on a larger scale, a detail from FIG. 1.

FIG. 4 is a section through FIG. 3 along the line III- III including inserted heating element units packets 31, 32, 33.

FIG. 5 is a section along the line IV-IV of FIG. 4 on a larger scale.

FIG. 6 is a detail A from FIG. 2 showing in sectional view the locating elements.

FIG. 7 is a front-elevation detail, similar to FIG. 3, of an alternative embodiment where upper and lower isolating dampers 52, 53 are provided, which isolate the sector,in which the installation or removal of cold end heating element units packets is being effected.

FIG. 8 is a plan view of the upper damper 52 of FIG. 7.

FIG. 9 is a section along the line VIVI of FIG. 7 showing the lower damper 53.

In these examples the axis of the regenerative chamber is vertical and the cold end is located at the bottom.

Referring to FIG. 1, the heating gases are led to the stationary cylindrical regenerative chamber from above through the fixed heating gas inlet duct 41 in direction of arrow 42. They flow through the upper, stationary part of the regenerative matrix 1 and a lower, rotatable heat-exchange element carrier 7, which they leave through the rigid lower heating gas outlet duct 43.

The air, to receive heat, flows in the opposite direction from a lower rotatable air hood 44 through the rotatable carrier 7 and the upper stationary part of the regenerative matrix 1 towards an upper rotatable air hood 45 and from there into the stationary hot air duct, which has not been illustrated. The two air hoods 44, 45 are mounted for rotation coaxially in the cylindrically shaped regenerative chamber on a common shaft 46. Each connects two segment-shaped areas on each axial end surface of the regenerative matrix 1 with central air inlet and outlet openings of the stationary air ducts (not shown). The drive of the air hood shaft 46 is effected by a spur gear 47 at the circumference of the lower air hood 44 which engages a lateral gear 48 driven by a motor.

The non-rotating part of the regenerative matrix 1 in the region of the upper hot zone (see left hand side of FIG. 2) is subdivided over its height 11 by fixed radial partition walls 2 and cylindrical intermediate walls 5, 6 giving segment-shaped chambers in which assemblies of metal heating elements 36, 37, 38 are arranged for heat exchange in the axial direction.

In the right half of FIG. 2 can be seen in section the rotatable carrier 7 at the cold end of the matrix. The carrier 7 extends over a height h of the regenerative chamber 1. In the carrier 7 there are units comprising assemblies of cold end heating surface elements 31, 32, 33 which units can be installed radially from outside the chamber through an aperture 40 in the chamber wall 4 of the regenerator chamber. The height h of the rotatable carrier 7 amounts to about 20 to 35 percent of the total height H of the stationary regenerative matrix l.

The aperture 40 is closed by a removable door and is of arcuate length slightly greater than the width of the largest heat exchange element unit 31. Rotation of the carrier 7 makes each radial set of units 31, 32, 33

selectively removable.

From FIGS. 1 and 3 it can be seen that an inner cylindrical core 3 of the stationary part of the regenerative matrix 1 which has an internal diameter d, and height h is bordered at its downward end by a lower annulus 8, which is firmly welded to the core 3 and is reinforced by an identical upper annulus 8a, which is rigidly arranged at a distance of about 0.1 to 0.2 of h above and parallel to the first annulus 8. The annuli 8 and 8a can be connected as shown by further stiffening elements and form a rigid support for a detachably fixed inner bearing-ring 10 carrying the rotatable carrier 7.

FIG. 3 shows a possible way of attaching by means of bolts 11 the inner bearing ring 10 to the annuli 8, 8a. The bearing ring 10 has approximately an L-shape in section and provides a shoulder facing away from the cold end on which the hub 12 of the rotatable carrier 7 is supported for rotation coaxially with the wall of the regenerative matrix 1 on rollers or other bearing elements 13.

As can be seen in particular in FIGS. 2 and 4, the rotatable cold end carrier 7 consists of the inner hub 12 and radial partition walls 2a, which are fixed thereon in a detachable manner. At their lower edges these sector partition walls 2a are detachably connected to each other by flat bars 14, 15, 16, which are arranged chordally, and by diagonal reinforcement bars 14a, 15a, 16a bracketing the bars 14, 15, 16, to the radial walls 2a.

The number and angular spacing of the radial partition walls 2a are the same as that of the walls 2 of the stationary part of the matrix with which in operation they can be kept in axial alignment by means of releasable locating elements 50 which lock the carrier 7 against rotation (see FIG. 6) in selected positions.

When installed between two radial partition walls 2a each, the cold end heating surface units 31, 32, 33 are gages from the outside through the cylindrical outer casing wall of the regenerative chamber intothe aperture of the angle piece 51. FIG. 6 also shows one of a plurality of resilient metal-plate strips 27, with which the radial partition walls 2a are provided at their radially outer edges and which abut sealingly against the inner side of the outer chamber wall 4 of the regenerative chamber.

By means of links 55 the rotatable carrier 7 can be detachably coupled for rotation to the cold end hood 44. Preferably there are two or more links 55 spaced equally circumferentially and at a common radial distance from the regenerator chamber axis.

In order to be able to maintain undisturbed operation of the air preheater during the installation or removal of the cold end heating element assemblies 31, 32, 33 it is of advantage, at least in an air preheater of larger dimensions, to be able to isolate the specific sectors in which installation or removal is performed at their upper and lower side from the gas flow.

In the embodiment of FIG. 7 one sector-shaped metal slide plate (damper) 52, 53 is radially inserted on each side of the rotatable carrier 7, one above and one below the region in which the replacement of the cold end supported on the lower flat bars 14, 15, 16 and 14a,

15a, 16a and they are kept spaced from each other by an outer holding bracket 31a on the radially outer heating element unit 31.

In FIG. 5 there is represented an arrested position of the rotatable cold end carrier 7 in which the upper and lower sector partition walls 2, 2a lie in common radial planes. At the upper edges of the rotatable partition walls 2a between them and the fixed partition walls 2 replaceable elastic sealing lamellae 25 are arranged for sealing and in gas-tight manner abut against U-shaped wear shoes 26 which are fixed on and enclose the lower edges of the stationary partition walls 2. This Figure shows furthermore the section through a cold end heating element unit 32, in which the metal heat-exchange elements have been represented, however, only schematically as have the lower diagonal flat bars 15a on which this unit is supported. On the upper edge of the sector partition wall 2a at the left there is shown one of the apertured angle pieces 51 which engages the locating pin as shown in FIG. 6. The locating pin 50,

which can be, for example, a hexagon headscrew, en-

heating surface units is effected i.e. above and below the aperture 40 through which the units pass. For this purpose flat bars 14b, 15b arranged in parallel and in chordal directions, are fixed in the upper, stationary part of the regenerative matrix 1 below the lower edges of the circumferential stationary chamber walls 5 and 6. The spacing of the flat bars 14b, 15b from the lower edges of the walls 5, 6 is only a little greater than the thickness of the upper metal slide plate 52. The slide plate 52 is inserted into the chamber through a slot 52a in the regenerative chamber wall 4. It is supported on the flat bar webs 14b, 15b and at its sides its radial edges closely fit against to the fixed radial partition walls 2 in a sealing manner.

In the same manner the lower isolating damper 53 is inserted through a slot 53a in the external wall of the regenerative chamber and is supported on lower flat iron webs 14c, 15c, 16c, whilst it sealingly abuts against the lateral radial partition walls 2a of the rotatable carrier 7.

The advantages achieved by this invention consist in that the installation and the removal of the heating surface elements and of their supporting structure in the region of the cold end zone, which elements and structure are particularly endangered by corrosion, can be effected in a radially direction from the outside through the aperture 40 of the regenerative chamber in a comparatively short time and that, if required, operation of the regenerative air preheater can be continued during performance of these operations.

What is claimed is:

1. A regenerative air preheater having a cylindrical regenerator matrix having two axial ends one being a hot end and the other a cold end, the said matrix being stationary during operation of the preheater, a coaxial rotatable hood at each said axial end to lead one of the heating gas and the heat-receiving gasto and away from the ends, a stationary wall surrounding the said matrix, and an aperture of restricted arc length in the said wall adjacent the cold end only, the said matrix being subdivided axially into two parts, both containing heat-exchange elements having heat exchanging surfaces, the said part at the hot end being fixedly stationary and the said part at the cold end including a rotatable heat-exchange element carrier axially aligned with the said aperture, whereby rotation of the said carrier selectively allows access to the said heat-exchange elements in the said rotatable carrier through the said aperture for their radial installation or removal.

2. A regenerative air preheateragcording to claim 1 wherein the said rotatable heat-exchange element carrier occupies between about and 35 percent of the axial length of the regenerator matrix between the said ends.

3. A regenerative air preheater according to claim 1 wherein a disconnectable drive from the hood is provided for driving the said carrier in rotation.

4. A regenerative air preheater according to claim 1 wherein the heat exchange space of the said rotatable carrier is partitioned by radial walls into radially extending wedge-shaped spaces, each of which in turn can be accessible from the aperture.

5. A regenerative air preheater according to claim 4 wherein means are provided for closing off the axial ends of the said wedge-shaped space, which is accessible at a given time, comprising two damper plates insertable through slots to both axial sides of the apertures.

6. A regenerative air preheater according to claim 1 wherein the heat exchange elements carried by the said rotatable carrier are assembled in a plurality of structural units, each unit being removable through the said aperture.

7. Regenerative air preheater according to claim 1 wherein radial partition walls arranged in the stationary part of the cylindrical regenerative matrix are rigidly connected to the outer cylindrical chamber wall of the matrix and an inner cylindrical core of the stationary part of the matrix the said core being ended towards the cold end by a first annulus which is firmly Welded to the core and is reinforced by a second annulus which is rigidly secured to the core parallel to and axially beyond the first annulus, the spacing of the at a distance annuli being about 0.1 to 0.2 of the length of the stationary chamber part.

8. Regenerative air preheater according to claim 7 wherein the said annuli are at their circumference rigidly secured to the said cylindrical core and connected with each other by axial stiffening elements thereby forming a rigid supporting structure at the cold end of the core on which a coaxial inner bearing ring for the rotatable carrier is detachably fixed.

9. Regenerative air preheater according to claim 8 wherein the said inner bearing ring has inits radially outer face a shoulder facing towards the hot end on which a hub of the rotatable carrier is movably supported on rolling bearing elements. I

10. Regenerative air preheater according to claim 4 wherein the said radial walls of the rotatable carrier are equally circuniferentially spaced and are secured at the inner hub of the carrier and at their bottom edges are detachably connected with each other by bars arranged in chordal directions said bars being at approximately equal radial distances from each other and being braced to adjoining sector partition walls through diagonally extending bars.

11. Regenerative air preheater according to claim 1 wherein at least one pair of radial partition walls of the rotatable carrier correspond in plan to at least one pair of radial partition walls in the non-rotatable part of the regenerator matrix there being means for holding releasably the rotatable carrier againstrotation with the sets of partition walls axially aligned.

12. Regenerative air preheater according to claim 1 wherein radial partition walls of the rotatable carrier are provided with resilient sealing elements which, in

gastight manner, engage sealing elements on corresponding fixed radial partition walls of the non-rotating part of the cylindrical regenerator matrix.

13. Regenerative air preheater according to claim 1 wherein radial partition walls of the rotatable carrier are provided at vertically extending radially outermost edges with radially resilient vertically extending metal plate strips, which in gastight manner engage a peripherally inner cylindrical surface of the outer chamber wall around the cylindrical regenerator matrix.

14. Regenerative air preheater according to claim 1 wherein the rotatable carrier is detachably connectable to the rotatable cold end hood by means of at least two coupling links which are distributed at equal circumferential spacings on at the same radial'distance from the axis.

15. In a regenerative air preheater having an operationally stationary axially divided cylindrical regenerator matrix in a stationary chamber, the improvement comprising a rotatable heat-exchange element carrier at the cold end only of the matrix and a closable aperture in the chamber wall at the cold end, access being possible selectively to peripheral portions of the rotatable carrier through the aperture by rotation of the carrier. 

1. A regenerative air preheater having a cylindrical regenerator matrix having two axial ends one being a hot end and the other a cold end, the said matrix being stationary during operation of the preheater, a coaxial rotatable hood at each said axial end to lead one of the heating gas and the heat-receiving gas to and away from the ends, a stationary wall surrounding the said matrix, and an aperture of restricted arc length in the said wall adjacent the cold end only, the said matrix being subdivided axially into two parts, both containing heat-exchange elements having heat exchanging surfaces, the said part at the hot end being fixedly stationary and the said part at the cold end including a rotatable heat-exchange element carrier axially aligned with the said aperture, whereby rotation of the said carrier selectively allows access to the said heat-exchange elements in the said rotatable carrier through the said aperture for their radial installation or removal.
 2. A regenerative air preheater according to claim 1 wherein the said rotatable heat-exchange element carrier occupies between about 20 and 35 percent of the axial length of the regenerator matrix between the said ends.
 3. A regenerative air preheater according to claim 1 wherein a disconnectable drive from the hood is provided for driving the said carrier in rotation.
 4. A regenerative air preheater according to claim 1 wherein the heat exchange space of the said rotatable carrier is partitioned by radial walls into radially extending wedge-shaped spaces, each of which in turn can be accessible from the aperture.
 5. A regenerative air preheater according to claim 4 wherein means are provided for closing off the axial ends of the said wedge-shaped space, which is accessible at a given time, comprising two damper plates insertable through slots to both axial sides of the apertures.
 6. A regenerative air preheater according to claim 1 wherein the heat exchange elements carried by the said rotatable carrier are assembled in a plurality of structural units, each unit being removable through the said aperture.
 7. Regenerative air preheater according to claim 1 wherein radial partition walls arranged in the stationary part of the cylindrical regenerative matrix are rigidly connected to the outer cylindrical chamber wall of the matrix and an inner cylindrical core of the stationary part of the matrix the said core being ended towards the cold end by a first annulus which is firmly welded to the core and is reinforced by a second annulus which is rigidly secured to the core parallel to and axially beyond the first annulus, the spacing of the at a distance annuli being about 0.1 to 0.2 of the length of the stationary chamber part.
 8. Regenerative air preheater according to claim 7 wherein the said annuli are at their circumference rigidly secured to the said cylindrical core and connected with each other by axial stiffening elements thereby forming a rigid supporting structure at the cold end of the core on which a coaxial inner bearing ring for the rotatable carrier is detachably fixed.
 9. Regenerative air preheater according to claim 8 wherein the said inner bearing ring has in its radially outer face a shoulder facing towards the hot end on which a hub of the rotatable carrier is movably supported on rolling bearing elements.
 10. Regenerative air preheater according to claim 4 wherein the said radial walls of the rotatable carrier are equally circumferentially spaced and are secured at the inner hub of the carrier and at their bottom edges are detachably connected with each other by bars arranged in chordal directions said bars being at approximately equal radial distances from each other and being braced to adjoining sector partition walls through diagonally extending bars.
 11. Regenerative air preheater according to claim 1 wherein at least one pair of radial partition walls of the rotatable carrier correspond in plan to at least one pair of radial partition walls in the non-rotatable part of the regenerator matrix there being means for holding releasably the rotatable carrier against rotation with the sets of partition walls axially aligned.
 12. Regenerative air preheater according to claim 1 wherein radial partition walls of the rotatable carrier are provided with resilient sealing elements which, in gastight manner, engage sealing elements on corresponding fixed radial partition walls of the non-rotating part of the cylindrical regenerator matrix.
 13. Regenerative air preheater according to claim 1 wherein radial partition walls of the rotatable carrier are provided at vertically extending radially outermost edges with radially resilient vertically extending metal plate strips, which in gastight manner engage a peripherally inner cylindrical surface of the outer chamber wall around the cylindrical regenerator matrix.
 14. Regenerative air preheater according to claim 1 wherein the rotatable carrier is detachably connectable to the rotatable cold end hood by means of at least two coupling links which are distributed at equal circumferential spacings on at the same radial distance from the axis.
 15. In a regenerative air preheater having an operationally stationary axially divided cylindrical regenerator matrix in a stationary chamber, the improvement comprising a rotatable heat-exchange element carrier at the cold end only of the matrix and a closable aperture in the chamber wall at the cold end, access being possible selectively to peripheral portions of the rotatable carrier through the aperture by rotation of the carrier. 